PICTURES: Sanders and Clinton visit Philadelphia

JESSICA KOURKOUNIS / GETTY IMAGES

Democratic presidential candidate Sen. Bernie Sanders (D-VT) speaks at a rally at Temple University on April 6, 2016 in Philadelphia, Pennsylvania. The Pennsylvania Democratic Primary is scheduled for April 26, 2016.

Democratic presidential candidate Sen. Bernie Sanders (D-VT) speaks at a rally at Temple University on April 6, 2016 in Philadelphia, Pennsylvania. The Pennsylvania Democratic Primary is scheduled for April 26, 2016. (JESSICA KOURKOUNIS / GETTY IMAGES)

A supporter of Democratic presidential candidate Sen. Bernie Sanders (D-VT) at a rally at Temple University on April 6, 2016 in Philadelphia, Pennsylvania. The Pennsylvania Democratic Primary is scheduled for April 26, 2016.

A supporter of Democratic presidential candidate Sen. Bernie Sanders (D-VT) at a rally at Temple University on April 6, 2016 in Philadelphia, Pennsylvania. The Pennsylvania Democratic Primary is scheduled for April 26, 2016. (JESSICA KOURKOUNIS / GETTY IMAGES)